Ireland's Scott Evans failed to trouble the great Lin Dan as the Olympic champion launched his title defence with an emphatic victory.

The Chinese superstar, widely regarded as the greatest player of all time, was barely extended by the Dubliner as he eased to a 21-8 21-14 victory in their first-round match at Wembley Arena.

The victory sees Lin go straight through to the last-16 knockout phase at London 2012 as the pair were the only players in Group P.

Evans had described the match as the biggest of his life and made a confident start as the crowd, with no Britons to cheer all day, got behind him.

The world number 76 hit a couple of good winners in the opening exchanges but Lin, despite playing well within himself, soon asserted his authority.

A run of seven unanswered points put Lin, seeded only second behind his great rival Lee Chong Wei, in command.

He controlled the rallies with ease and often only had to wait long enough for Evans to hit the net.

Evans did break through occasionally with some fine cross-court shots, much to the delight of those watching, but it did not delay the inevitable Lin victory for long.

Evans felt he did not do himself any favours during the 34-minute contest.

The 24-year-old said: "I thought it went horrendously. You have to be at the top when you play Lin Dan, he is the best ever to play badminton.

"If you are a little bit off your best you are going to have a hard day, and I had a hard day.

"I was a little bit stretched all the time because he is on the shuttle all the time.

"He is just unbelievable. He doesn't make errors at all and if you give him a chance he just takes it every time."

Lin gave the impression that he was holding himself back for tougher contests ahead.

He said: "It is only the first match and there are still strong opponents to come in the next matches, so I will continue to give it my all."

World number one Lee Chong Wei survived a huge scare before booking his place in the last 16.

The top seed was taken to three games by unheralded Finn Ville Lang in a late-night thriller at Wembley Arena, but produced a strong finish to prevail 21-8 14-21 21-11.

Lee had been troubled in the build-up to London 2012 by an ankle injury and showed signs of rustiness as world number 45 Lang fought back in the second game.

Although the Malaysian eventually came through by winning 10 of the last 11 points, his performance will offer encouragement to his rivals.

Lee, who plans to retire after the Games, said: "I am only mentally strong because I have had an injury and I am still not 100%.

"But I had nothing to lose and I just tried my best."

Lang said he had been inspired by the sight of Finnish president Sauli Niinisto in the crowd.

He said: "That was spectacular for me. I have never played before such a prestigious audience.

"I saw him come in before the match and thought, 'Oh f*** what am I going to do now? I need to play well'.

"Fortunately I played the best game of my life."

Danish veteran Peter Gade, playing his fourth and last Olympics at the age of 35, started his latest bid for gold with an easy win over Portugal's Pedro Martins.

Watched by Crown Prince Frederik, the 2000 semi-finalist and fifth seed won 21-15 21-8.

The day's highest-profile casualty of the day was Japan's eighth seed Kenichi Tago, who crashed out after a shock loss to Sri Lanka's Niluka Karunaratne.

Karunaratne, the world number 48, won 21-18 21-16 in 46 minutes, and Tago admitted he did not know what hit him.

He said: "It felt like I woke up from sleep and the next thing I know I had already lost. I don't know what happened."

The women's singles eighth seed Sung Ji-hyun of South Korea was also knocked out, going down 21-18 23-21 in a nailbiter to Hong Kong's world number 22 Yip Pui Yin.

The big guns in the women's singles had no such trouble.

Chinese pair Wang Yihan and Wang Xin, seeds one and two respectively, both reached the last 16 with comfortable wins in the morning session.

Visitors in the afternoon were robbed of a potentially thrilling finish in a men's doubles match between Thailand's Bodin Isara and Maneepong Jongjit and the Poles Adam Cwalina and Michal Logosz.

The Polish pair were trailing 17-15 in a deciding game when Logosz snapped an Achilles tendon landing awkwardly after jumping.

He left the arena in a wheelchair and the Thais won by default.

America's 2005 world champions Howard Bach, 33, and Tony Gunawan, 37, announced their retirement after going down to a third successive loss in the men's doubles, this time to Japan's Naoki Kawamae and Shoji Sato.

Bach said: "I'm ready to call it a day. Well never say never I suppose but there is a 0.00000% chance I may be back."

Korean Lee Yong-dae saw his hopes of defending the mixed doubles title ended as he and new partner Ha Jung-eun lost 21-15 21-12 to Danes Thomas Laybourn and Kamilla Rytter Juhl.

China's Chen Jin, the fourth seed, wrapped up the day's play by beating Pole Przemyslaw Wacha 21-15 21-8.